1 #include <linux/compiler.h> 2 #include <linux/types.h> 3 #include <unistd.h> 4 #include "tests.h" 5 #include "debug.h" 6 #include "machine.h" 7 #include "event.h" 8 #include "unwind.h" 9 #include "perf_regs.h" 10 #include "map.h" 11 #include "thread.h" 12 #include "callchain.h" 13 14 /* For bsearch. We try to unwind functions in shared object. */ 15 #include <stdlib.h> 16 17 static int mmap_handler(struct perf_tool *tool __maybe_unused, 18 union perf_event *event, 19 struct perf_sample *sample __maybe_unused, 20 struct machine *machine) 21 { 22 return machine__process_mmap2_event(machine, event, NULL); 23 } 24 25 static int init_live_machine(struct machine *machine) 26 { 27 union perf_event event; 28 pid_t pid = getpid(); 29 30 return perf_event__synthesize_mmap_events(NULL, &event, pid, pid, 31 mmap_handler, machine, true, 500); 32 } 33 34 #define MAX_STACK 8 35 36 static int unwind_entry(struct unwind_entry *entry, void *arg) 37 { 38 unsigned long *cnt = (unsigned long *) arg; 39 char *symbol = entry->sym ? entry->sym->name : NULL; 40 static const char *funcs[MAX_STACK] = { 41 "test__arch_unwind_sample", 42 "unwind_thread", 43 "compare", 44 "bsearch", 45 "krava_3", 46 "krava_2", 47 "krava_1", 48 "test__dwarf_unwind" 49 }; 50 51 if (*cnt >= MAX_STACK) { 52 pr_debug("failed: crossed the max stack value %d\n", MAX_STACK); 53 return -1; 54 } 55 56 if (!symbol) { 57 pr_debug("failed: got unresolved address 0x%" PRIx64 "\n", 58 entry->ip); 59 return -1; 60 } 61 62 pr_debug("got: %s 0x%" PRIx64 "\n", symbol, entry->ip); 63 return strcmp((const char *) symbol, funcs[(*cnt)++]); 64 } 65 66 __attribute__ ((noinline)) 67 static int unwind_thread(struct thread *thread) 68 { 69 struct perf_sample sample; 70 unsigned long cnt = 0; 71 int err = -1; 72 73 memset(&sample, 0, sizeof(sample)); 74 75 if (test__arch_unwind_sample(&sample, thread)) { 76 pr_debug("failed to get unwind sample\n"); 77 goto out; 78 } 79 80 err = unwind__get_entries(unwind_entry, &cnt, thread, 81 &sample, MAX_STACK); 82 if (err) 83 pr_debug("unwind failed\n"); 84 else if (cnt != MAX_STACK) { 85 pr_debug("got wrong number of stack entries %lu != %d\n", 86 cnt, MAX_STACK); 87 err = -1; 88 } 89 90 out: 91 free(sample.user_stack.data); 92 free(sample.user_regs.regs); 93 return err; 94 } 95 96 static int global_unwind_retval = -INT_MAX; 97 98 __attribute__ ((noinline)) 99 static int compare(void *p1, void *p2) 100 { 101 /* Any possible value should be 'thread' */ 102 struct thread *thread = *(struct thread **)p1; 103 104 if (global_unwind_retval == -INT_MAX) 105 global_unwind_retval = unwind_thread(thread); 106 107 return p1 - p2; 108 } 109 110 __attribute__ ((noinline)) 111 static int krava_3(struct thread *thread) 112 { 113 struct thread *array[2] = {thread, thread}; 114 void *fp = &bsearch; 115 /* 116 * make _bsearch a volatile function pointer to 117 * prevent potential optimization, which may expand 118 * bsearch and call compare directly from this function, 119 * instead of libc shared object. 120 */ 121 void *(*volatile _bsearch)(void *, void *, size_t, 122 size_t, int (*)(void *, void *)); 123 124 _bsearch = fp; 125 _bsearch(array, &thread, 2, sizeof(struct thread **), compare); 126 return global_unwind_retval; 127 } 128 129 __attribute__ ((noinline)) 130 static int krava_2(struct thread *thread) 131 { 132 return krava_3(thread); 133 } 134 135 __attribute__ ((noinline)) 136 static int krava_1(struct thread *thread) 137 { 138 return krava_2(thread); 139 } 140 141 int test__dwarf_unwind(void) 142 { 143 struct machines machines; 144 struct machine *machine; 145 struct thread *thread; 146 int err = -1; 147 148 machines__init(&machines); 149 150 machine = machines__find(&machines, HOST_KERNEL_ID); 151 if (!machine) { 152 pr_err("Could not get machine\n"); 153 return -1; 154 } 155 156 callchain_param.record_mode = CALLCHAIN_DWARF; 157 158 if (init_live_machine(machine)) { 159 pr_err("Could not init machine\n"); 160 goto out; 161 } 162 163 if (verbose > 1) 164 machine__fprintf(machine, stderr); 165 166 thread = machine__find_thread(machine, getpid(), getpid()); 167 if (!thread) { 168 pr_err("Could not get thread\n"); 169 goto out; 170 } 171 172 err = krava_1(thread); 173 thread__put(thread); 174 175 out: 176 machine__delete_threads(machine); 177 machine__exit(machine); 178 machines__exit(&machines); 179 return err; 180 } 181